When you are measuring the performance of your website there are several important metrics; visits, unique visitors, page views and pages per visit are fairly self explanatory. Bounce rate is essentially a measure of behaviour which includes how quickly people leave your website after visiting. It is a key measure of relevance and this is something that is very important in the Google algorithm.
I measure a number of sites and I have noticed that bounce rate tends to increase to a small degree over time even on a website where all of the other metrics are holding or improving. I'm specifically talking about relatively stable long established websites. It seems that bounce rate is prone to rising slightly over time, whereas the aim is for it to be falling. Why might this be?
Internet users are becoming more experienced and better and quicker at getting to the information that they are searching for. This means that bounce rate will naturally be a little higher this year than last given the same sort of user behaviour.
One of the challenges of SEO is making sure that you are matching search queries to content. You can always improve bounce rate by working on this challenge regularly. However, I believe that increasing competence on the users' side means that, all things being equal, bounce rate will reflect their improving performance online. This means that bounce rate does tend to naturally increase.
One solution is to spread content over a number of pages, to encourage users to move around in your site. However, you risk reducing content on your pages and this counts against you. You might fill out the pages with more words, but then you risk frustrating users and they will leave and go elsewhere.
The best solution is to build FAQ pages and case studies and link these to your content. This will not stop all bounces but you will manage to reduce rates by percentages, and that is what this game is all about.
So get to know your bounce rates. If you use a SEO consultant ask them to give you a list of the pages in your website with the highest bounce rates and build useful content around them.